<template>
    <div @click.stop="back" class="music-list">
        <div class="back">
            <i class="icon-back"></i>
        </div>
        <h1 class="title" v-html="title"></h1>
        <div class="bg-image" :style="bgStyle" ref="bgImage">
            <div class="play-wrapper">
                <div class="play" v-show="songs.length>0" ref="playBtn" @click.stop="random">
                    <i class="icon-play"></i>
                    <span class="text">随机播放全部</span>
                </div>
            </div>
            <div class="filter"></div>
        </div>
        <div class="bg-layer" ref="layer">
        </div>
        <scroll @scroll="scroll" :probe-type="probeType" :listen-scroll="listenScroll" :data="songs" class="list" ref="list">
            <div class="song-list-wrapper">
                <song-list @select="selectItem" :songs="songs" :rank="rank"></song-list>
            </div>
            <div class="loading-container" v-show="!songs.length">
                <loading></loading>
            </div>
        </scroll>
    </div>
</template>

<script type="text/ecmascript-6">
import Scroll from 'base/scroll/scroll'
import SongList from 'base/song-list/song-list'
import Loading from 'base/loading/loading'
import {prefixStyle} from 'common/js/dom'
import {mapActions} from 'vuex'

import {playlistMixin} from 'common/js/mixin'


const RESET_HEIGHT =40;
const transform = prefixStyle('transform')
const backdrop = prefixStyle('backdrop-filter')

export default {
    mixins:[playlistMixin],
    props:{
        bgImage:{
            type:String,
            default:''
        },
        songs:{
            type:Array,
            default:[]
        },
        title:{
            type:String,
            default:''
        },
        rank:{
            type:Boolean,
            default:false
        }
    },
    data(){
        return {
            probeType:1,
            listenScroll:true,

            scrollY:0,
            imageHeight:0
        }
    },
    computed:{
        bgStyle() {
            return `background-image:url(${this.bgImage})`
        }
    },
    created() {
        this.probeType=3
        this.listenScroll=true
    },
    mounted(){
        this.imageHeight=this.$refs.bgImage.clientHeight;
        this.minTranslateY= -this.imageHeight+RESET_HEIGHT;
        this.$refs.list.$el.style.top=`${this.imageHeight}px`
    },
    methods: {
        handlePlaylist(playlist){
            const bottom = playlist.length > 0 ? '60px':''
            this.$refs.list.$el.style.bottom = bottom
            this.$refs.list.refresh()
        },


        scroll(pos){
            this.scrollY=pos.y
            console.log(pos.y)
        },
        back(){
            this.$router.back()
        },
        // 接受song-list派发的选中播放歌曲的事件
        selectItem(item,index) {
            console.log(item,index)
            this.selectPlay({
                list:this.songs,
                index
            })
        },
        random () {
            console.log(this.songs)
            this.randomPlay({
                list:this.songs
            })
        },
        
        ...mapActions([
            'selectPlay',
            'randomPlay'
        ])
    },
    
    watch:{
        scrollY(newY){
            let translateY =Math.max(this.minTranslateY,newY);
            let zIndex=0;
            this.$refs.layer.style[transform]=`translate3d(0,${translateY}px,0)`

            if(newY<this.minTranslateY){
                zIndex=10;
                this.$refs.bgImage.style.paddingTop=0
                this.$refs.bgImage.style.height=`${RESET_HEIGHT}px`
                this.$refs.playBtn.style.display='none'
            }else {
                this.$refs.bgImage.style.paddingTop='70%'
                this.$refs.bgImage.style.height=0
                this.$refs.playBtn.style.display=''
            }
            this.$refs.bgImage.style.zIndex=zIndex;
        }
    },

    components:{
        Scroll,
        SongList,
        Loading
    }
};
</script>

<style scoped lang="stylus" rel="stylesheet/stylus">
@import '~common/stylus/variable';
@import '~common/stylus/mixin';

.music-list {
    position: fixed;
    z-index: 100;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    background: $color-background;

    .back {
        position: absolute;
        top: 0;
        left: 6px;
        z-index: 50;

        .icon-back {
            display: block;
            padding: 10px;
            font-size: $font-size-large-x;
            color: $color-theme;
        }
    }

    .title {
        position: absolute;
        top: 0;
        left: 10%;
        z-index: 40;
        width: 80%;
        no-wrap();
        text-align: center;
        line-height: 40px;
        font-size: $font-size-large;
        color: $color-text;
    }

    .bg-image {
        position: relative;
        width: 100%;
        height: 0;
        padding-top: 70%;
        transform-origin: top;
        background-size: cover;

        .play-wrapper {
            position: absolute;
            bottom: 20px;
            z-index: 50;
            width: 100%;

            .play {
                box-sizing: border-box;
                width: 135px;
                padding: 7px 0;
                margin: 0 auto;
                text-align: center;
                border: 1px solid $color-theme;
                color: $color-theme;
                border-radius: 100px;
                font-size: 0;

                .icon-play {
                    display: inline-block;
                    vertical-align: middle;
                    margin-right: 6px;
                    font-size: $font-size-medium-x;
                }

                .text {
                    display: inline-block;
                    vertical-align: middle;
                    font-size: $font-size-small;
                }
            }
        }

        .filter {
            position: absolute;
            top: 0;
            left: 0;
            width: 100%;
            height: 100%;
            background: rgba(7, 17, 27, 0.4);
        }
    }

    .bg-layer {
        position: relative;
        height: 100%;
        background: $color-background;
    }

    .list {
        position: absolute;
        top: 0;
        bottom: 0;
        width: 100%;
        background: $color-background;

        .song-list-wrapper {
            padding: 20px 30px;
        }

        .loading-container {
            position: absolute;
            width: 100%;
            top: 50%;
            transform: translateY(-50%);
        }
    }
}
</style>
